Identification of hepatitis C virus seroconversion resulting from nosocomial transmission on a haemodialysis unit: Implications for infection controland laboratory screening

Hepatitis C virus (HCV) seroconversion was detected by routine screening in a haemodialysis patient, Patient 1. Serological investigations were undert aken over the following 3 months to determine if further transmission to ot her patients on the unit had occurred. No additional cases were identified. Twenty-two haemodialysis patients known to have HCV infection were investi gated using molecular epidemiological methods to determine if transmission between patients had occurred. HCV viraemia was demonstrated by polymerase chain reaction in 19 of 22 patients (86%). Genotyping showed that eight pat ients were infected with genotype 1, three with genotype 3 and eight, inclu ding Patient 1, with genotype 2. Phylogenetic analysis of viral sequences f rom the eight patients with genotype 2 revealed three, including Patient 1, with a novel subtype of HCV type 2, and revealed close similarity between v iral sequences from patient 1 and those from one other patient, suggesting transmission. This was consistent with haemodialysis histories. Among other patients with genotype 2, there were two with subtype 2a and three others with three separate novel subtypes, as yet undesignated. With the exception of patient 1, all patients infected with novel subtypes were of Afro-Carib bean origin. The HCV prevalence among patients on the haemodialysis unit wa s high (14%), which may reflect the ethnicity of our haemodialysis populati on. This case emphasises the risk of nosocomial transmission and the import ance of infection control procedures on haemodialysis units, and highlights the usefulness of molecular epidemiological techniques for the investigati on of outbreaks of HCV infection. (C) 1999 Wiley-Liss, Inc.